Add copy rete limiter

copy.go

@@ -83,15 +83,21 @@ func fcopy(src, dest string, info os.FileInfo, opt Options) (err error) {
 
 	var buf []byte = nil
 	var w io.Writer = f
-	// var r io.Reader = s
+
+	var r io.Reader = s
+	if opt.CopyRateLimit > 0 {
+		r = NewRateLimitedReader(r, opt.CopyRateLimit)
+	}
+
 	if opt.CopyBufferSize != 0 {
 		buf = make([]byte, opt.CopyBufferSize)
 		// Disable using `ReadFrom` by io.CopyBuffer.
 		// See https://github.com/otiai10/copy/pull/60#discussion_r627320811 for more details.
 		w = struct{ io.Writer }{f}
 		// r = struct{ io.Reader }{s}
 	}
-	if _, err = io.CopyBuffer(w, s, buf); err != nil {
+
+	if _, err = io.CopyBuffer(w, r, buf); err != nil {
 		return err
 	}
 

go.mod

@@ -4,5 +4,6 @@ go 1.14
 
 require (
 	github.com/otiai10/mint v1.4.0
+	go.uber.org/ratelimit v0.2.0
 	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8
 )

go.sum

@@ -1,8 +1,27 @@
+github.com/andres-erbsen/clock v0.0.0-20160526145045-9e14626cd129 h1:MzBOUgng9orim59UnfUTLRjMpd09C5uEVQ6RPGeCaVI=
+github.com/andres-erbsen/clock v0.0.0-20160526145045-9e14626cd129/go.mod h1:rFgpPQZYZ8vdbc+48xibu8ALc3yeyd64IhHS+PU6Yyg=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/otiai10/curr v0.0.0-20150429015615-9b4961190c95/go.mod h1:9qAhocn7zKJG+0mI8eUu6xqkFDYS2kb2saOteoSB3cE=
 github.com/otiai10/curr v1.0.0 h1:TJIWdbX0B+kpNagQrjgq8bCMrbhiuX73M2XwgtDMoOI=
 github.com/otiai10/curr v1.0.0/go.mod h1:LskTG5wDwr8Rs+nNQ+1LlxRjAtTZZjtJW4rMXl6j4vs=
 github.com/otiai10/mint v1.3.0/go.mod h1:F5AjcsTsWUqX+Na9fpHb52P8pcRX2CI6A3ctIT91xUo=
 github.com/otiai10/mint v1.4.0 h1:umwcf7gbpEwf7WFzqmWwSv0CzbeMsae2u9ZvpP8j2q4=
 github.com/otiai10/mint v1.4.0/go.mod h1:gifjb2MYOoULtKLqUAEILUG/9KONW6f7YsJ6vQLTlFI=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
+go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
+go.uber.org/ratelimit v0.2.0 h1:UQE2Bgi7p2B85uP5dC2bbRtig0C+OeNRnNEafLjsLPA=
+go.uber.org/ratelimit v0.2.0/go.mod h1:YYBV4e4naJvhpitQrWJu1vCpgB7CboMe0qhltKt6mUg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

options.go

@@ -46,6 +46,10 @@ type Options struct {
 	// See https://golang.org/pkg/io/#CopyBuffer for more information.
 	CopyBufferSize uint
 
+	// Limit the rate of copying files with n KB per second.
+	// If zero, will not limit the copy operation.
+	CopyRateLimit int64
+
 	intent struct {
 		src  string
 		dest string
@@ -92,6 +96,7 @@ func getDefaultOptions(src, dest string) Options {
 		Sync:              false,              // Do not sync
 		PreserveTimes:     false,              // Do not preserve the modification time
 		CopyBufferSize:    0,                  // Do not specify, use default bufsize (32*1024)
+		CopyRateLimit:     0,                  // Do not specify, use default rate (unlimited)
 		intent: struct {
 			src  string
 			dest string

ratelimited_reader.go

@@ -0,0 +1,38 @@
+package copy
+
+import (
+	"io"
+
+	"go.uber.org/ratelimit"
+)
+
+type RateLimitedReader struct {
+	src     io.Reader
+	limiter ratelimit.Limiter
+}
+
+// NewRateLimitedReader
+// n means the number of Kb to be read per second
+func NewRateLimitedReader(src io.Reader, n int64) io.Reader {
+	return &RateLimitedReader{
+		src:     src,
+		limiter: ratelimit.New(int(n)),
+	}
+}
+
+func (lr *RateLimitedReader) Read(p []byte) (n int, err error) {
+	n, e := lr.src.Read(p)
+	if e != nil && e != io.EOF {
+		return n, e
+	}
+	if n > 0 {
+		nkb := n / 1024
+		if nkb == 0 {
+			nkb = 1
+		}
+		for i := 0; i < nkb; i++ {
+			lr.limiter.Take()
+		}
+	}
+	return n, e
+}